The present invention relates to portable sheet bending brakes.
Sheet bending brakes heretofore proposed generally include a support frame formed by a pair of elongated support rails and a plurality of C-shaped frame sections that interconnect the rails. An elongated base member is mounted on the lower arms of the frame sections to form a clamp surface, and an elongated anvil member is mounted on bars pivotally secured to the upper arms of the frame sections for clamping sheet material against a clamp surface on the base member. A bend member is pivotally mounted to the base member for bending over the anvil member sheet material clamped between the anvil member and the base member. Among problems associated with conventional portable sheet bending brakes of this type is difficulty in storing and transporting the brake between jobs. Manufacturers recommend against suspending the brakes from hangers that engage the frame rails, which can bend or distort the brakes. Handles on the bend member must be removed prior to transport, still leaving mounting posts or the like extending beneath the support plane of the frame, which can catch on clothing or frame support surfaces. Another problem with conventional brakes lies in the fact that some assembly is typically required before the brake is ready for use by a purchaser.
The present invention provides a number of aspects or improvements in sheet bending brakes. These aspects or improvements may be implemented separately from each other, or more preferably in combination with each other, as in the preferred embodiment of the invention herein disclosed. In accordance with one aspect of the invention, the handle or handles coupled to the bend member of the sheet bending brake, to assist an operator in manually bending the sheet material over the anvil member, are mounted to the bend member to pivot between a position extending from the bend member for use by an operator and a position adjacent to the bend member. In the latter position, the handle or handles are effectively folded out of the way and do not obstruct storage of the bending brake. In accordance with another aspect of the invention, the arms that pivotally mount the anvil member to the frame sections have handle openings adjacent to the anvil member for grasping by a user to facilitate transport of the brake. Yet another aspect of the invention contemplates securement of the frame sections to the frame rails on three sides of the rails, so that the brake may be suspended from hooks by the front or rear rail, for example, without distorting or bending the rear rail or the brake assembly.
In accordance with another aspect of the present invention, a shaft extends through bearings on the upper arms of the frame sections. Eccentric cams are mounted on the shaft and engage the anvil member support arms for pivoting the support arms and the anvil member toward and away from the clamp member as a function of rotation of the shaft. The shaft has a non-uniform lateral cross section, preferably including diametrically opposed longitudinally extending channels parallel to the axis of the shaft. The eccentric cams are of integrally formed construction, and have non-uniform openings, preferably with diametrically opposed lugs, received over the shaft so that the cams are automatically timed with respect to each other and with respect to the shaft upon assembly of the cams to the shaft. This aspect of the invention addresses problems in prior art constructions of this type, in which the cams are mounted on collars that must be rotationally timed with respect to the shaft, and in which the cams may readily become misaligned and mistimed during use of the bending brake. The shaft support bearings mounted in the upper arms of the frame sections have elongated tapering openings for accommodating movement of the shaft to clamp the anvil member and the sheet material in position. These bearings have tapering outer surfaces that cooperate with tapering outer surfaces in the frame section arms to facilitate manufacture in that the bearings may be inserted in the arms in only one direction. The elongated bearing slots allow clamping of a wide range of sheet material thicknesses, are self-adjusting, and do not require manual adjustment with wear as weather changes.
Yet another aspect of the present invention contemplates a stand and table assembly for a sheet bending brake, including a stand for mounting the brake above a horizontal surface such as the ground, and a table mounted on the stand for movement between a lowered position beneath the brake and a raised position adjacent to the clamp surface of the brake. In the preferred embodiment, the stand includes multi-bar linkages mounting the table to the frame for maintaining horizontal orientation of the table at and between the lowered and raised positions. The frame includes locks for locking the table in the raised position, and springs for assisting manual raising of the table from the lowered to the raised position.